An Acoustic Emission Method for Assessing the Degree of Degradation of Mechanical Properties and Residual Life of Metal Structures under Complex Dynamic Deformation Stresses.

Petr Louda,Artem Sharko,Dmitry Stepanchikov

doi:10.3390/ma14092090

Petr Louda, Artem Sharko + Show 1 more

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https://doi.org/10.3390/ma14092090

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Abstract

An acoustic emission method for assessing the degree of degradation of mechanical properties under conditions of complex dynamic deformation stresses is proposed. It has been shown that changing the operating conditions of metal structures, peak loads, external collisions, and thermally changing loads, which cannot be taken into account, leads to uncertainty and unpredictable structural changes in the material. This in turn makes it difficult to identify the state of the structure material to ensure trouble-free operation of the equipment. Changes in the mechanical properties under difficult loading conditions are identified by polynomial approximation of the results of AE measurements and the construction of boundary curves separating the operability region from the fracture region. This is achieved by approximating the experimental dependences of the acoustic parameters for various types of loading. This approach significantly expands the capabilities of the technical means of identification systems of metal structures, and in particular, allows the current state of the equipment and its suitability for further operation to be assessed without stopping the equipment in real time. It is of interest not only to fix the damage, but also to diagnose the processes of reducing the mechanical properties during the operation of the equipment.

Highlights

IntroductionPublisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations
The conditions for the performance of the material will be the fulfillment of the conditions σt < σB or εt < εB for tensile deformation and σb < σ0.2 or εb < ε0.2 for bending deformation
To use the obtained experimental data to determine the degradation of the mechanical properties of materials under difficult loading conditions, the correspondence of the relative deformation on the density N of the AE signals was approximated εt (N) for tensile and bending εb (N)

Summary

Introduction

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Determination of the degree of degradation of mechanical properties and the residual life of metal structures under complex dynamic deformation stresses has various applications related to bending, tensile static and dynamic loads, and processes of the initiation of defects. The trouble-free operation of metal structures relies on the monitoring of their technical condition and the implementation of physical diagnostic methods. The need to conduct an industrial safety examination exists for equipment that has fully run its service life or has been used under conditions not prescribed by the standards, when emergency situations may have occurred, which may affect the performance of the material

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